Thermionic amplifier and oscillation generator



Aug. 18, 193]. H. ROUND 1,319,845

THERMIONIC AMPLIFIER AND OSCILLATION GENERATOR Filed July 19, 1926 INVENTOR. HENRY JOSE PH ROUND ATTORNEY Patented Aug. 18, 1931 Emir JDSiE-PH 'RonNn-or Lennon, nNeLaivn; ,nss1eivoR--roLimmocontentmen i I OF'-A1VIER;ICAF, .A:CORPORA'DIQN-OE nnmwmnnwq j' I rnnamonrcnmrmmnnnun oscrnrnmioiv cinnamon g 'l his.-:.invention-rel-ates to th'ermionic li'fieis and the like.

The object of the present invention is" to provide am amplifier in wh-ich' tlie eifect of reaction and undesired coupling, due to the inter-electrode capacity of thermionic valves, is avoided.

Several means for avoiding the reaction between the electrodes of a thermionic valve are known, such means including a balancing condenser arranged in electrostatic o-pposition to the self-capacity existing between the electrodes of the valve. In such arrangements it is usual to provide an inductance and capacity in parallel in the anodecircuit of the valve whose grid anode capacity it is desired to neutralize, and the neutralizing or balancing condenser is sometimes connected between the end of the inductance and capacity remote from the anode and the grid, the point of zero or earth potential being arranged to be part of the way along the inductance. 7

An arrangement of this kind, however,

, eastill leaves degrees of freedom for unwanted oscillations. i

According to the present invention the inductances employed in the anode circuits of a plurality of valves in a multi-valve ampliau fier, oscillation generator or the like, of the type having anti-reaction means, are wound some of them to be astatic (i. e. so that the 'net magnetic fields, due to currents flowing therein, are practically zero or greatly re- 3a=:duced at external points) and others nonastatic, and these are arranged in a mixed mainductance of each half with respect to the rest of the apparatus is in the opposite sense to that of the other half. Unwanted oscillations in other degrees of freedom can be prevented by this arrange ment, which, whilemaintaining the same in du'c'tanee were wanted natural 'period in both 1 static and: astatie' coils, rentlers the in duct'ancei for I other" methods; o't emanate verywhfierentQ- The" invention is-illustratediin the aeooin anyings drawing whiehrshows inwdiagnanr matie:fonn 'an,ampiifienhaiving threerval ves in'c'ascade- W r Reierring:tothe drimring llis a 'thermibninii valve in who'se anode circuitfii included an: anode condenser 2; and "an anedeinductances: formed of two halves aa andeti l -i'S aL ba1 ancin g" con-densen oonnected to the #griidznfin: the thermionic waive -=1 andiof suuh; values as to' camp en's'atie' in known mannen :for the; self a capacityo'fithe saiiiivalvea 'Ehe anode-oi w cuit" is completed throughfithe 'anoderb attery 5 f roma poinu between the ha'lves 3a and=i3b= ot the anodeinductan'ce.zfElie circuitsa 'of the valves 6,37 aresimi lan, likeznumerals in dicating like pants-. The anodei 'inductaincel of- "thevalve 1! is woundito be astatirrathat Ofif the v'alveio non astan c;and.thatzoiistheivalvew 7 astatic. c 1 Initheifigureuonly suclripants asiare necessarytoi explain: the invention-.PhaveFbeen: shown :for examplegi the" filament heating: batteryand: its; associatedconnections have beemomitt'edu i h i avin described meeavenebmmatin e cl'a'im'isf p 1 i I Y 1 In: an: impedance resistance coupled: cascade: relay havingva vacuunntubeain eachi stage thereofimeaiis 'foweoup'lingg the-vacuum? tubesdofrth'ea severalirstages including in:-'=85-: ductance' between: adjacent; stagessrcoinposedi oattwoiportiongzoneio'fiwhijchiisinthewritnut Y circuit: of. the preceding; tube; alternating on'esfofi saidsindii'ctancessbeingastatioto pre 2 vent electromagnetic; coupling between said a stages; and1means in. each stage: providing a.

path Eton neutralizing: the inherent "feed?" back between: the; outputciandl inputfi circuits oi each stage.

2 In:a cascade amplifiershaving aj vacuumxwai tubeiin eachistagetheneofi meansi'torrcouplingf' the vacuum tubes of the several stageseincludw: ingr ani inductance" betweem' adjacent stages saidiincluctancea havingtwo portionsaone: of: which is; connecteditoi the output elementsioft m the preceding tube, alternating ones of said inductances being wound astatic to prevent electro-magnet coupling between stages, and a capacity connecting another portion of each of said inductances to the grid electrode of the preceding tube to neutralize the inherent capacity between the grid and anode electrodes thereof.

3. In radio apparatus, a thermionic tube having anode, cathode and grid electrodes, an input circuit including an inductance associated with the grid and cathode of said tube, an output circuit connected between said anode and said cathode,cand an inductance consisting of'two astatic wound portions, one of which is connected in series in the output circuit ofsaid tube, the other portion of said inductance being connected through a capacity to the grid of said tube whereby the anode to gridcapacity ofsaid tube is compensated and magnetic coupling between the input and output circuits of said valve is prevented.

4. In radio apparatus, a plurality of thermionic tubes each having anode, cathode and grid electrodes, an input circuit including an inductance associated with the grid and cathode of one of said tubes, an inductance consisting of two astatic wound portions one of which is connected between the anode and cathode of said tube, the other portion of said inductance being connected to thegrid of said tube, means for coupling the anode electrode of said last named tube to the grid electrode of the other of said tubes including a coupling condenser, a resistance connected be-,

said cathode, an output circuit including an inductance having two portions one of which is connected-between the anode and cathode of said tube, capacity means for connecting the other portion of said inductance to the grid electrode of said tube, asecond thermionic tube having anode, cathode and grid electrodes, a capacity connecting the anode electrode of said first named tube to the grid electrode of said second named tube, a resistance connected between the grid and cathode of said 'lastnamed tube, an output circuit comprising a portion of an astatic wound inductance connected between the anode and cathode of said last named tube and capacity means connecting another portion of said inductance to the grid electrode of said last named tube.

6. In an impedance coupled thermionic amplifier, a'plurality of thermionic tubes, each having anode, cathode and grid eleceach tube, alternate ones' of the said inductances having thetwo portions wound so as to be astatic to prevent electromagnetic coupling between the stages, capacitive means connecting the anode electrode of each of said tubes to the grid electrode of the following tube, and a resistance connection between the grid and cathode of each of said last named tubes.

HENRY JOSEPH ROUND. 

